Address resolution in telecommunications signaling networks refers to the process of translating an unroutable address into a routable address. In conventional telecommunications signaling networks, address resolution has been performed based on numeric identifiers, such as the mobile subscriber integrated services digital network (MSISDN) number or the international mobile station identity (IMSI). For example, in signaling system #7 (SS7) signaling networks, the global title address located in the signaling connection control part (SCCP) or mobile application part (MAP) of a message may contain MSISDN number. Global title translation at a signal transfer point may translate the numeric global title address into a point code and subsystem number or an Internet protocol (IP) address corresponding to the destination for the message. Similarly, in Diameter signaling messages, MSISDNs and IMSIs have been resolved into addresses for destination realms and destination hosts.
With the advent of Internet of things (IoT) devices, the number of user entities or devices is expected to increase multifold. Due to the anticipated increase in number of devices, using the MSISDN or IMSI to identify such devices may not be practical because the number space may not accommodate large numbers of devices.
To account for this number space deficiency, IoT devices can be identified using an external identifier. The external identifier is defined in 3rd Generation Partnership Project (3GPP) Technical Specification (TS) 23.003, “Technical Specification Group Core Network and Terminals; Numbering addressing and identification,” Release 15, September 2018, the disclosure of which is incorporated herein by reference in its entirety. According to 3GPP TS 23.003, the external identifier is an identifier used to facilitate communications with packet data networks and applications, such as machine type communications (MTC) applications on the external network. The form for the external identifier is:                <local identifier>@<domain identifier>        
The domain identifier is specified as a newly registered Internet domain name according to Internet Engineering Task Force (IETF) Request for Comments (RFC) 4282, “The Network Access Identifier” (December 2005), the disclosure which is incorporated herein by reference in its entirety. According to 3GPP TS 23.682, “Technical Specification Group Services and System Aspects; Architecture enhancements to facilitate communications with packet data networks and applications,” Release 16, September 2018, the disclosure of which is incorporated herein by reference in its entirety, the external identifier identifies the subscription associated with an IMSI and a local identifier may be a number. For example, in Section 19.7.2, 3GPP 23.682 specifies the following as an example of an external identifier:                123456789@domain.com.        
As described above, traditional address resolution relies on numeric parameters, such as the MSISDNs or IMSIs. If devices are identified using external identifiers instead of MSISDNs and IMSIs, conventional numeric-only address resolution will not be able to resolve the external identifiers into routable addresses.
Even in instances where address resolution based on the external identifier is performed, the address resolution may not result in a sufficiently granular division of services in a service provider's network. For example, if external identifier address resolution is performed based solely on an exact match of the domain component of the external identifier, there is no ability to segregate services based on subdomains within a service provider's domain or based on different MTC device groups within the service provider's domain.
Accordingly, there exists a need for methods, systems, and computer readable media for Diameter signaling message external identifier address resolution and routing.